Chipotle Mexican Grill is doing a Facebook Places "Deal" this weekend: If you "check in" to a Chipotle restaurant this weekend on Facebook, you get buy-one, get-one free burritos, salads, tacos, etc.

In response, Foursquare cofounder and CEO Dennis Crowley told his Twitter followers to petition @ChipotleMedia -- Chris Arnold, a comms./media guy at Chipotle -- to set up a Foursquare deal in addition.

Crowley tweeted, "If you heart @foursquare and delicious Chipotle burritos, you should tell @ChipotleMedia to run a 4SQ promo!"

Turf war!

So far, it appears that hundreds of people have tweeted at Chipotle, demanding respect for Foursquare. But so far, Chipotle still seems to be just pushing the Facebook deal. Though Arnold, the Chipotle media guy, is egging the Foursquare fans on: "Just FB Places this time. But let me hear from you #foursquare fans and I'll plead the case."

Perhaps Chipotle will try a Foursquare deal in weeks to come?

Or perhaps this is a sign that Facebook's massive scale is going to be more of a problem for Foursquare than they thought?